In a theoretical model, a rotating circular saw blade may be compared to a rotating disk divided into annular segments including (1) a circumferential cutting edge or rim (2) connected by a "middle" radially extended segment to (3) a "central" drive collar that is connected to a power source at the center blade "eye." It is evident that the centrifugal force of a powered, rotating blade, at any annular ring at a given radius from the blade center, is proportional to the radial distance of the ring from the driven blade center.
The cutting edge of one type of metal saw blade contains cutting "teeth" separated by "gulletts" spaced about the peripheral circumference of the blade in a predetermined pattern. The teeth may be of a material different from the metal blade disk; for example, carbide teeth are frequently employed. Or in some blades, such as diamond segment saws used for cutting masonry and other hard materials, the blade rim or circumference includes an abrasive cutting material (e.g., diamond powder) intrinsically bonded to the saw body surface at its outer circumferential section.
As the blade is in use while cutting a material, the circumferential rim of the blade, the blade teeth and/or discrete sections of the blade are subjected to various stresses, which in turn are distributed as a force or combination of forces through the blade disk.
In wood cutting, for example, a sudden inconsistency encountered in the density of the wood cut, such as a knot, may result in a "shock" force transmitted in the blade which results in a tooth break, a separation of a carbide tooth from the blade body, or a crack in the blade body propagating from the blade gullett. Such occurrences may lead to a blade stress failure.